There are numerous types of circuit board components in use today, including those which have been specifically developed for high current and high power applications, such as for electrical vehicles. A current component used in these applications is a TO247 package. These devices utilize metalized ceramic substrates, stamped copper leads or lead frames, wire bonds, or solderable topside integrated circuits (ICs). There are a variety of solderable topside packages for use with discreet power devices and integrated circuits. One of these devices utilizes a plastic material to overmold the TO247 package except for the bottom surface. The plastic overmold protects the internal die and wire bonds or bond straps. The bottom surfaces in most instances are electrically attached and thermally conductive. It is typically left open to provide a thermal and electrical path out of the package. This path also allows the end user to connect the package to a heat sinking mass or an electrical bus.
With these prior devices, a heat sink pad must be added in order to achieve electrical isolation. The pad, however, adds thermal resistance to the assembly, typically on the order of 0.1 to 0.5 degrees per C./watt.